Air bearings support a load by allowing a rotation shaft to float due to pressure of compressed air between the rotation shaft and a bearing.
In the air bearing, when a gas having viscosity, such as air, moves along with a movable surface and meets a stationary surface, the gas is compressed and a pressure of air trapped between the movable surface and the stationary surface increases, thereby lifting the movable surface.
The air bearing may a thrust air bearing that supports a load applied in a lengthwise direction of the rotation shaft or a journal air bearing that supports a load applied in a radial direction with respect to the rotation shaft.
Another type of the thrust air bearing is a thrust foil air bearing which uses a foil of a thin material to facilitate formation of pressure and improve dynamic stability at high speed.
A thrust foil air bearing 1 according to the related art, as illustrated in FIG. 11, may include a bottom plate 2 that is a plate member coupled to a stationary portion S, a bump foil 3 arranged on an upper surface of the bottom plate 2 and elastica deformable, and a top foil 4 arranged above the bump foil 3 and contactable with a rotating portion R. The rotating portion R is coupled to a rotation shaft F rotating in a preset rotation direction W around a centerline C.
In the thrust foil air bearing 1, the bump foil 3 and the top foil 4 are coupled to the upper surface of the bottom plate 2 by welding. When the bump foil 3 and the top foil 4 are coupled to the bottom plate 2 by welding, the entire structure of the bearing is simplified and initial product development costs and mold manufacturing costs may be reduced. However, several series of manufacturing processes such as a press process and a welding process are required and manufacturing welding jigs and welding quality management are needed. Thus, the thrust foil air bearing is disadvantageous in terms of product price management and quality management and thus is not suitable for mass production.